Turbocharger with magnetic brake

ABSTRACT

Turbochargers are disclosed that have a braking system to brake the rotation of an electrically conductive compressor wheel within the turbocharger. The brake system includes the electrically conductive compressor wheel, which is connected to a turbine by a common shaft, one or more electromagnets positioned proximate to the compressor wheel, and a control circuit electrically coupled to the one or more electromagnets to turn the one or more electromagnets on or off to provide braking action to the compressor wheel. Systems including such a turbocharger and methods utilizing such turbochargers are also included herein.

TECHNICAL FIELD

This application relates to turbocharger systems within internalcombustion engines, more particularly, to exhaust-driven turbochargershaving a magnetic brake.

BACKGROUND

Internal combustion engines, its mechanisms, refinements and iterationsare used in a variety of moving and non-moving vehicles or housings.Today, for example, internal combustion engines are found in terrestrialpassenger and industrial vehicles, marine, stationary, and aerospaceapplications. There are generally two dominant ignition cycles commonlyreferred to as gas and diesel, or more formally as spark ignited andcompression ignition, respectively. More recently, exhaust-driventurbochargers have been incorporated into the system connected to theinternal combustion engine to improve the power output and overallefficiency of engine.

Turbochargers are generally incorporated to increase engine performance.In such applications, turbochargers often require control of their speed(the RPMs at which the turbine or compressor wheel rotates) so thateither compressor surge or over speed does not occur. Typically, turbospeed control is accomplished by valves, levers and/or actuated devicesthat bypass exhaust gas around the turbine housed in the turbine sectionof the turbocharger. These types of controls include several movingparts that can wear over the life of the turbocharger and ultimatelywear out.

There is a need to continue to improve the exhaust-driven turbochargers,including the efficiency, power, and control thereof, in particular theturbo speed control.

SUMMARY

In one aspect, turbochargers are disclosed herein that can replace oraugment the turbo speed control previously existing, such as thataccomplished by valves, levers, and actuated devices, by including abraking system for the compressor wheel utilizing Lenz's law. Here, anon-contacting, non-friction brake system is disclosed that includes oneor more electromagnets positioned proximate to the compressor wheel,which is electrically conductive, and a control circuit electricallycoupled to the one or more electromagnets to turn the one or moreelectromagnets on or off to provide braking action to the compressorwheel. When the electromagnet(s) are activated the magnetic fieldgenerated thereby brakes the compressor wheel and as a result reducesthe turbo speed of the turbocharger.

In another aspect, a system is disclosed that includes the turbochargerdescribed in the preceding paragraphs and an internal combustion enginein fluid communication therewith. The system may also include an enginecontrol unit that communicates with the control circuit of the brakesystem to turn the electromagnet(s) on or off as needed. In oneembodiment, the control circuit receives commands from the enginecontrol unit to activate the electromagnet(s) to brake the compressorwheel in coordination with at least one engine function to avoid a surgein the compressor section of the turbocharger or over revving of theturbine.

In another aspect, methods for controlling the rotational speed of aturbocharger are disclosed. The method may include providing aturbocharger such as those described herein having electromagnet(s) anda control circuit, and operating the control circuit to allow electriccurrent to flow to the one or more electromagnets to create a magneticfield to slow the rotations of the compressor wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram including flow paths and flow directions of oneembodiment of an internal combustion engine turbo system.

FIG. 2 is a side, perspective view of one embodiment of a turbocharger.

FIG. 3 is an end, perspective, partially assembled view of theturbocharger of FIG. 2.

FIG. 4 is a longitudinal cross-sectional view of the turbocharger ofFIG. 2.

DETAILED DESCRIPTION

The following detailed description will illustrate the generalprinciples of the invention, examples of which are additionallyillustrated in the accompanying drawings. In the drawings, likereference numbers indicate identical or functionally similar elements.

FIG. 1 illustrates one embodiment of an internal combustion engine turbosystem, generally designated 100. The turbo system 100 includes thefollowing components in controlling the operating parameters of aturbocharger: an exhaust-driven turbocharger 102 having a turbinesection 104 that includes a housing 112 having an inlet opening 113 andan exhaust outlet 114 and a compressor section 106 that includes ahousing 116 having an ambient air inlet 118 and a discharge opening 119.Housed within housing 112 of the turbine section 104 is a turbine wheel124 that harnesses and converts exhaust energy into mechanical workthrough a common shaft 125 to turn a compressor wheel 126 that ingestsair from an air induction system 150, compresses it and feeds it athigher operating pressures into the engine inlet 162 of the internalcombustion engine 160.

Still referring to FIG. 1, the compressor section 106 of theturbocharger 102 is in fluid communication with various parts of thesystem as follows: (1) the ambient air inlet 118 of the compressorsection 106 is in fluid communication with the air induction system 150and, optionally, return passages 138 from a compressor bypass valve 140;and (2) the discharge opening 119 is in fluid communication with theintake manifold of the internal combustion engine 160. The intakemanifold is represented by passageway 152, engine inlet 162, and intakevalves contained therein (not shown). The turbine section 104 of theturbocharger 102 is in fluid communication with other parts of thesystem as follows: (1) the exhaust inlet 113 is in fluid communicationwith an exhaust manifold of the internal combustion engine; and (2) theexhaust outlet 114 is in fluid communication with passage 174 (alsoreferred to as the exhaust line) exhausting to a catalytic converter176. The exhaust manifold is represented in FIG. 1 by engine exhaust 164and passageway 172. Additionally, a turbine bypass valve 130, commonlyreferred to as a wastegate, may be present. The turbine bypass valve 130may be in fluid communication with a source of fluid to operate anactuator, such as actuator 134 in FIG. 2, that controls the opening andclosing of the bypass valve 130. When the bypass valve 130 is opened,wasted exhaust gas from the internal combustion engine 160 bypasses theturbine section 104 of the turbocharger 102 by being diverted throughthe bypass valve 130 and flowing directly to the exhaust line 174. Assuch the turbine bypass valve 130 controls the amount of exhaust gasentering the turbine section 104 of the turbocharger 102.

Now referring to FIGS. 2-4, one embodiment of the turbocharger 102 isshown. As discussed above, the turbocharger 102 has a turbine section104 and a compressor section 106, both having respective housings 112,116. As illustrated in FIGS. 3 and 4, an electrically conductivecompressor wheel 126 is enclosed within housing 116 of the compressorsection 106. The electrically conductive compressor wheel 126 isconnected to the turbine 124, enclosed within housing 112 of the turbinesection 104, by a common shaft 125. Here, the added feature is a brakingsystem that includes one or more electromagnets 128 positioned proximateto the compressor wheel 126, and a control circuit 120 electricallycoupled to the one or more electromagnets 128, for example by wires,cables, and/or electrical connectors 122, to turn the one or moreelectromagnets 128 on or off to provide braking action to the compressorwheel 126. The electromagnets 128, when on (i.e., activated), create amagnetic field that will slow down the electrically conductivecompressor wheel 126 per Lenz's law. Accordingly, the electromagnets 128act as a non-contact, non-friction brake to control the rotational speedof the compressor wheel 126 and hence the common shaft 125 and theattached turbine 124.

As seen in FIGS. 2 and 4, the control circuit 120 may independentlycontrol the electromagnets 128 to provide the braking action to thecompressor wheel 126 or may be electrically coupled to an engine'sengine control unit 166, from which the control circuit 120 will receivecommands or signals directing the operations of the control circuit. Theengine control unit 166 can send signals to control circuit 120 toactivate the electromagnets 128 under an engine condition likely tocause a surge of the compressor wheel 126 or under an engine conditionthat would over rev the turbine, thereby avoiding the surge or the overrev. Similarly, the engine control unit 166 can send signals to controlcircuit 120 to de-activate the electromagnets 128 under selected engineconditions when boost is demanded, for example, rapid vehicleacceleration.

As seen in FIGS. 3 and 4, the one or more electromagnets 128 arepositioned proximate the compressor wheel 126 at a location between theambient air inlet 118 and a side of the compressor wheel 180 facing theambient air inlet 118. The electromagnets may be embedded in a surface117 of the housing 116 enclosing the compressor wheel 126. In anotherembodiment, the electromagnets 128 may be mounted to a surface, such assurface 117, of housing 116 by any means. Also, the electromagnets 128may be positioned more proximal to an edge 182 of the compressor wheel126 defining the compressor wheel's outer diameter than a bore 184defining the compressor wheel's inner diameter, and may be mounted orembedded equally distant from one another in a concentric arrangementabout the central longitudinal axis A of the turbocharger.

In one embodiment, the electromagnets 128 may be composed of an ironcore with coils of wire wound around the core. The electromagnetsprovide the ability to control the strength of the magnetic fluxdensity, the polarity of the field, and the shape of the field. Thestrength of the magnetic flux density is controlled by the magnitude ofthe current flowing in the coil, the polarity of the field is determinedby the direction of the current flow, and the shape of the field isdetermined by the shape of the iron core around which the coil is wound.Additionally, the braking system may be controlled and/or adjusted bychanging the number of electromagnets, their spacing, orientation, andlocation relative to the compressor wheel.

The braking system in the turbocharger 102 has many benefits overconventional methods of turbine speed control, especially over by-passsystems using valves, levers and actuators. One benefit is theutilization of the magnetic fields created by the electromagnets in thatthe electromagnets act very fast to provide braking, which reducesresponse time and allow increased turbo performance. Accordingly, theturbo speed (surge) safety margins can be reduced due to theinstantaneous turbo speed braking action. Another benefit is that thebraking system has no moving parts other than the compressor wheel,which was already present. The electromagnetic braking system providesthe additional benefit of being a variable controlled system byelectronically controlling the strength of the magnetic field. Thisproportional braking provides greater turbo speed control by applyingonly the minimum braking required to maintain proper turbine/compressorwheel speed.

As discussed above, the braking system can avoid surge or over revving,which could result in catastrophic failure of the turbocharger. This inturn would prevent engine catastrophic damage from the engine ingestingdebris from the turbocharger failure.

Having described the invention in detail and by reference to preferredembodiments thereof, it will be apparent that modifications andvariations are possible without departing from the scope of theinvention which is defined in the appended claims.

What is claimed is:
 1. A turbocharger comprising: an electricallyconductive compressor wheel connected to a turbine by a common shaft;one or more electromagnets positioned proximate to the compressor wheel;and a control circuit electrically coupled to the one or moreelectromagnets to turn the one or more electromagnets on or off toprovide braking action to the compressor wheel.
 2. The turbocharger ofclaim 1, wherein the control circuit is electrically coupled to anengine control unit and receives a signal therefrom to control thebraking of the compressor wheel in coordination with at least one enginefunction to avoid a surge of the compressor wheel or over revving of theturbine.
 3. The turbocharger of claim 1, wherein the one or moreelectromagnets are positioned between an ambient air inlet and a side ofthe compressor wheel facing the ambient air inlet.
 4. The turbochargerof claim 3, wherein the one or more electromagnets are positioned moreproximal to an edge of the compressor wheel defining the compressorwheel's outer diameter than a bore defining the compressor wheel's innerdiameter.
 5. The turbocharger of claim 1, wherein the one or moreelectromagnets is a plurality of electromagnets mounted equally distantfrom one another in a concentric arrangement about a centrallongitudinal axis of the turbocharger.
 6. The turbocharger of claim 1,wherein the one or more electromagnets are embedded in a surface of ahousing enclosing the compressor wheel.
 7. The turbocharger of claim 1,further comprising a wastegate operatively connected in a fluid flowpathleading to an exhaust inlet in fluid communication with the turbine. 8.A method for controlling the rotational speed of a turbocharger, themethod comprising: providing a turbocharger having an electricallyconductive compressor wheel connected to a turbine by a common shaft anda braking system comprising one or more electromagnets positionedproximate to the compressor wheel and a control circuit electricallycoupled to the one or more electromagnets to turn the one or moreelectromagnets on or off to provide braking action to the compressorwheel; operating the control circuit to allow electric current to flowto the one or more electromagnets to create a magnetic field to slow therotations of the compressor wheel.
 9. The method of claim 8, furthercomprising: operating the control circuit to stop the flow of electriccurrent to the one or more electromagnets.
 10. The method of claim 8,wherein the one or more electromagnets are positioned between an ambientair inlet and a side of the compressor wheel facing the ambient airinlet.
 11. The method of claim 8, wherein the one or more electromagnetsare positioned more proximal to an edge of the compressor wheel definingthe compressor wheel's outer diameter than a bore defining thecompressor wheel's inner diameter.
 12. The method of claim 8, whereinthe one or more electromagnets is a plurality of electromagnets mountedequally distant from one another in a concentric arrangement about acentral longitudinal axis of the turbocharger.
 13. The method of claim8, wherein the one or more electromagnets are embedded in a surface of ahousing enclosing the compressor wheel.
 14. The method of claim 8,wherein the turbocharger is part of an engine system having an enginecontrol unit electrically coupled to the control unit, and the methodfurther comprises; sending signals from the engine control unit to thecontrol circuit to activate or de-activate the one or moreelectromagnets in coordination with at least one engine function. 15.The method of claim 8, further comprising a wastegate operativelyconnected in a fluid flowpath leading to an exhaust inlet in fluidcommunication with the turbine.